Checksum

[Per]

Hello

Can anyone tell me how to find the checksum (the byte before F7) in FmBox voice/drum or ensemble files?

Is it 7bit or 8bit notation, and from where to where will i have to count?

Regards Per

[TK.]

Hi Per,

the checksum is calculated over the data part only (256 bytes)

Calculation (pseudo code):

    // data block is located in data[] array

    // create sysex string:


    Array<uint8> sysEx;


    sysEx.add(0xf0);

    sysEx.add(0x00);

    sysEx.add(0x00);

    sysEx.add(0x7e);

    sysEx.add(0x49);

    sysEx.add(deviceNumber);

    sysEx.add(0x02);

    sysEx.add(type);

    sysEx.add(bank);

    sysEx.add(patch);


    uint8 checksum = 0x00;

    for(int i=0; i<256; ++i) {

        uint8 b = data[i];

        sysEx.add(b);

        checksum += b;

    }


    sysEx.add(-(int)checksum & 0x7f); // 7bit !!!

    sysEx.add(0xf7);

[/code]


Best Regards, Thorsten.

[Per]

Thank you Thorsten it was just what i needed

and thanks for the Fm Synth its a fantastic piece of work, and what a sound :thumbsup:

Best regards Per